My Indy will be changing mine as a maintenance item later this year _________________Me? The 13th Duke of Wybourne? Here? In a sixth form girl's dormitory? At three o'clock in the morning? With my reputation? What were they thinking of?

FourtuitousMonza

Joined: 27 Aug 2010Posts: 163Location: North Yorkshire

Posted: Mon Jul 03, 2017 2:54 pm Post subject:

I was planning to change the belt on mine as preventative maintenance because I had heard it can cause damage if the second distributor stops in the wrong place when the belt breaks. But after reading a "how to do it" article in one of the Porsche magazines I bottled out and asked my indie to fit exchange reconditioned dizzys with new Beru ignition lead set at the same time. I decided it was worth it for peace of mind and knowing that the complete distributors were as good as new rather than just the belt. Just checked my invoice. £964 including complete pair of Dizzy's, leads and labour. That was in 2013._________________Cars, cars, fast, fast! One is seized, filled with enthusiasm, with joy... the joy of power.
The simple and naive pleasure of being in the midst of power, of strength.
Le Corbusier, The City of Tomorrow, 1929.

decgrahamSuzuka

Joined: 17 Sep 2008Posts: 1108Location: Spain

Posted: Mon Jul 03, 2017 3:30 pm Post subject:

Hi,

As well as the link Zingari put up, here is another link to a guy who has a C4 and lives in Holland. I used his DIY to remove my steering rack and found his write up with pictures really helpful.

For a Yorkshireman that was a lot of dough _________________Me? The 13th Duke of Wybourne? Here? In a sixth form girl's dormitory? At three o'clock in the morning? With my reputation? What were they thinking of?

wozyImola

Joined: 06 Feb 2013Posts: 804Location: Worcestershire

Posted: Mon Jul 03, 2017 4:17 pm Post subject:

Blimey I hope you caught that quick. I was in Northway years ago and a bloke was paying for a rebuild on his 993 caused by the belt in the dizzys breaking._________________Porsche Cars of Great Britain launched the 993 in the UK in early December 1993 registering 12 x UK cars on the 6th & 7th of that month; mine is one of them.

I too have heard horror stories however mine must have broken on a 200 mile trip from Aberdeen to home and the only issue I noticed was a slight but noticeable power loss........had a look over the car last night and when I removed the caps and cranked the engine by hand noticed the secondary rotor wasn't turning - everything else looks good,only changed them a couple of years ago, so I suppose it depends where the rotor arm stops. It starts on the button and I will remove the coil lead from the secondary dizzy before driving it the 10 miles to the Indy.....

Chaps I have my distributer out at the moment and following the instructions on Dec's link above, seems fairly straightforward if handy with the tools otherwise I would leave it. You have to drill the old pin out and there's many parts that you need to understand how they go back together. Mine actually took some fairly gentle persuasion to come out of the block, which I can imagine if done with engine in situ would be a real pain.

Gives a good chance to clean up the block and dissis is places you can't easily reach.

Yes I can see why the labour cost would be high on this work.

Trev

A993LADNürburgring

Joined: 20 Mar 2007Posts: 469Location: Cambs

Posted: Fri Dec 08, 2017 12:09 pm Post subject:

Cameltoe & Heel wrote:

Chaps I have my distributer out at the moment and following the instructions on Dec's link above, seems fairly straightforward if handy with the tools otherwise I would leave it. You have to drill the old pin out and there's many parts that you need to understand how they go back together. Mine actually took some fairly gentle persuasion to come out of the block, which I can imagine if done with engine in situ would be a real pain.

Gives a good chance to clean up the block and dissis is places you can't easily reach.

Yes I can see why the labour cost would be high on this work.

Trev

This is a very interesting thread.

My car has done 126k miles and I can't find any record of the distributor belt ever being changed.

Having looked at the DIY links it looks relatively simple to remove the distributor unit. But then pretty complicated to get it apart and change the belt.

Is there a recommended supplier for a reconditioned exchange unit in the UK?

Also, if this is a waer and tear part that could have major implications when it fails, why on earth did Porsche position the belt inside the unit in a way where it needs to be entirely stripped down to install a replacement? That's just crazy.

Reminds me of replacing my alternator last year. I couldn't believe how much work and dismantling had to be undertaken to swap out the alternator for a reconditioned exchange unit compared to simply undoing two bolts on a normal car and completing the job in 10 minutes.

A993LADNürburgring

Joined: 20 Mar 2007Posts: 469Location: Cambs

Posted: Fri Dec 08, 2017 12:20 pm Post subject:

Good grief I just went on to the design 911 site to check if they sell, exchange unit distributors and they do.

Only £890 including VAT (plus £125 surcharge until the exchange unit is received)

That seems an awful lot of money to take somebody's old unit, open it up, change the belt, grease the bearings and put it back together again. Are there cheaper suppliers?

I see the list price for the belt and the pin is only £13, so maybe I will have a go at doing this myself afterall.

So do I spend my winter nights working on the 993 distributor, or do I fit the refurbished supercharger back on the Lagonda which is what I was planning to do?

Kat1Silverstone

Joined: 04 Nov 2010Posts: 125Location: Ely, Cambs

Posted: Fri Dec 08, 2017 1:07 pm Post subject:

I seem to recall a guy who wrote in one of the specialist Porsche mags had a crank failure on his 964.

This was the infamous Peppermint Pig.

I believe the crank snapped and this was attributed to broken distributor drive belt.

A993LADNürburgring

Joined: 20 Mar 2007Posts: 469Location: Cambs

Posted: Fri Dec 08, 2017 1:39 pm Post subject:

Kat1 wrote:

I seem to recall a guy who wrote in one of the specialist Porsche mags had a crank failure on his 964.

This was the infamous Peppermint Pig.

I believe the crank snapped and this was attributed to broken distributor drive belt.

Interesting

My next question was going to be how can a belt that does nothing apart from drive a little spinney thing outside of the engine cause catastrophic engine damage If it snaps?

I can understand it with a timing belt leaving valves in the down position when a piston comes up.

But if all spinney thing does is send Sparks to the spark plugs. Why does it damage main engine components when it stops spinning?

Marc

Kat1Silverstone

Joined: 04 Nov 2010Posts: 125Location: Ely, Cambs

Posted: Fri Dec 08, 2017 2:01 pm Post subject:

As I understand it the spark reacts with the atmosphere to produce ozone which has the chemical formula O3 compared with oxygen O2

Ozone is so corrosive that when used commercially (water purification, washing contaminated laundry etc) it has to be produced at site and cannot be transported as there is no vessel material that is suitable.

I know that in laundry applications standard rubber components had to be changed for a different material due to premature failure.

It is the ozone that"corrodes" the belt so when Porsche became aware of this they put a clear plastic breather on the distributor to remove this gas as part of ongoing technical updates.

Now the speculation -

a) Maybe the modification was designed and tested over a relatively short period so with cars over 20 years old the rubber has deteriorated sufficiently to break.

b) Maybe deterioration of other components manifests itself as a larger spark and more ozone.

c) Maybe 20 year rubber is not that great generally.

I bi annually check that both rotor arms are turning and if I was to notice a slight drop in power I would even check these items at the side of the road.

Just disconnect the lead from each coil to distributor in turn and see if the car starts.

A993LADNürburgring

Joined: 20 Mar 2007Posts: 469Location: Cambs

Posted: Fri Dec 08, 2017 2:17 pm Post subject:

Thanks

I think you've explained how the rubber belt would snap.

But the bit I don't understand is once the rubber belt has snapped and the second distributor stops spinning. Why would that cause significant damage to the engine at all?

Surely you just end up with one spark instead of two and life goes on?

Chris993C2Hockenheim

Joined: 09 Mar 2010Posts: 627Location: South Bucks

Posted: Fri Dec 08, 2017 2:49 pm Post subject:

A993LAD wrote:

But the bit I don't understand is once the rubber belt has snapped and the second distributor stops spinning. Why would that cause significant damage to the engine at all?

Surely you just end up with one spark instead of two and life goes on?

Depends where the rotor arm comes to rest - if it's on a contact, then that plug is going to be doing a lot of sparking...

decgrahamSuzuka

Joined: 17 Sep 2008Posts: 1108Location: Spain

Posted: Fri Dec 08, 2017 3:59 pm Post subject:

Hi All,

If you download the link I attached above you will see that Hans explains how to replace the belt only, which looks a lot easier than a full strip down like Trev is doing.

However, I have found the following outfit in Germany that offer different types of rebuilds, below is the cheapest.

I also contacted Peter Crago at Ignition car parts ltd (sales@ignitioncarparts.co.uk) but he came back to me and said that he had trouble getting the belt. As I was only checking out options I never went back to him, but finding the belt and the bearings is not an issue from the research I've done. Perhaps if you supplied the belt and bearings he would offer a price, at least he's UK based.

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